This invention relates to a method of cooling off a regenerative thermal oxidizer for shut down, to allow the regenerative thermal oxidizer to cool off much more quickly than has been the case in the prior art.
Regenerative thermal oxidizers are utilized to remove impurities from an industrial air stream. Thus, an air stream from an industrial process, such as a paint spray booth, is brought to a regenerative thermal oxidizer. Air with impurities to be removed passes in an inlet mode through a previously heated heat exchanger, and into a combustion chamber. The impurities are baked out of the air in the heat exchanger and combustion chamber. The air with the impurities entering the heat exchanger is relatively cool. Once combusted in the combustion chamber the air is hot, and leaves through a second heat exchanger which is in an outlet mode. The heat exchangers switch between the inlet and outlet modes, heating the inlet air, and cooling the outlet air. In some regenerative thermal oxidizers a "purge" mode is utilized to remove entrapped dirty air before switching to outlet mode from inlet mode.
Regenerative thermal oxidizers and the associated heat exchangers can reach very high temperatures. When internal maintenance or inspection of an RTO is required, it is first necessary to cool the combustion chamber and heat exchangers to near ambient temperatures. It is typical that this process will take between 18 and 36 hours if the RTO is cooled by simply turning off the combustion chamber burner.
Obviously, if a routine inspection or immediate maintenance is desired, it would be beneficial to cool the regenerative thermal oxidizer much quicker. In addition, it is inefficient to require a long cool-down time with the regenerative thermal oxidizer being shut down.